The present invention relates to polyvinyl chloride plastisol-based curable compositions.
In the manufacture of automobiles, the automobile body is initially primed with a coating composition to prevent corrosion of the metal. This can be done in a number of ways although generally it is performed by cationic electrodeposition using the auto body as the cathode. Once the automobile body has been primed in this manner, subsequent steps in the assembly are carried out. These steps typically include the use of sealants over the primed automobile body. The sealants are subsequently topcoated along with the remainder of the body during the final stages of the painting process.
A common and inexpensive variety of sealant which is utilized in automobile manufacture is the polyvinyl chloride plastisol-based sealant. These sealants generally require the addition of some type of adhesion promoter in order to achieve optimum adhesion to the primed metal auto body. Historically, polyaminoamides have been utilized in plastisol-based sealants as adhesion promotors for the composition. These adhesion promotors, however, have certain disadvantages associated with them. In particular, the polyaminoamides interfere with the acid catalyzed cure of the automobile topcoat and also they contribute to bleed-through yellowing of the automobile topcoat.
There is a need, therefore, for a polyvinyl chloride plastisol-based curable composition which has excellent adhesion to primed metal and also is capable of being topcoated with a variety of coating compositions without yellowing of the topcoat.